Control mechanism for underwater explosive charge



July 27, 1965 H. J. MACK ETAL CONTROL MECHANISM FOR UNDERWATER EXPLOSIVE CHARGE 2 Sheets-Sheet 1 Filed NOV. 30, 1960 F lg. 20

INVENTORS HAROLD J. MACK JOSEPH N. YACCARINO JOHN E. SMITH DONA D F. S TH ATTORNE y 27, 1955 H. J. MACK ETAL 3,196,790

CONTROL MECHANISM FOR UNDERWATER EXPLOSIVE CHARGE Filed Nov. 30, 1960 2 Sheets-Sheet 2 7 I I Q 53 o 53 52 l 362?. I, D 52 3o 31 0 61 I 59 6 14 18 "I, O 13 1 I -".II a o |I I ll I i I I I l I 69 I 9 I I I 1 0:0 F/g.7 59 $7 I I 72 1o s2 I INVENTORS 63 I HAROLD J. MACK l 61 5a JOSEPH N. YACCARINO BY JOHN E. SMITH DONAL F. MI S7 Arrow; 7

United States Patent CONTROL MECHANISM FOR UNDERi/VATER EXPLOSIVE CHARGE Harold J. Mack, Allentown, John E. Smith, Hathoro, and Joseph N. Yaccarinn and Donaid F. Smith, Norristown, Pa., assignors to the United States of America as represented by the Secretary of the Navy Filed Nov. 30, 1960, Ser. No. 72,896

7 Ciaims. (Cl. 102-18) (Granted under Title 35, US. Code (1952), see. 266) The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to an underwater explosive device of the type depending from a hydrofoil and used for detecting and destroying submerged marine mines, and more particularly to the control mechanism of such an underwater explosive device characterized by including provision for being automatically armed at a predetermined depth for releasing the device from the hydrofoil and for exploding it a predetermined time interval after becoming attached to a marine mine.

In marine mine sweeping operations, helicopters have become an important and very useful vehicle. A hydrofoil having means for maintaining itself below the surface of the water is dragged by a helicopter through an area to be cleared of submerged mines. A plurality of encased explosive charges provided with protruding magnets for attracting the charges to a ferromagnetic marine mine depend from the hydrofoil. A charge so attracted will cling to the marine mine and thereafter become detached from the hydrofoil and subsequently exploded, thereby destroying the mine. Such a mine sweeping method and apparatus therefor are disclosed in application Serial No. 793,939 of Donald F. Smith for Antimine Weapon, filed February 17, 1959.

The explosive charge device, or so called magnetic leech, must be a completely self-contained unit capable of being automatically armed when submerged to a predetermined depth in the water to assure against premature detonation, of being self-detaching from the hydrofoil when a mine is contacted, and of exploding a predetermined elapsed time thereafter. Conventional and existing hydrostatic arming devices and delay timers have been found unsuitable for the specific application to the magnetic leech and were heretofore unobtainable in acombined form that would perform the several functions in the order of operation as described above. Furthermore, if their combination were possible, an assembly would be produced which would be utterly too large for specific application to a magnetic leech. The mere reduction in part sizes of such existing conventional devices would render the device economically unfeasible, unreliable, and unsafe for the extensive and severe use contemplated.

Accordingly, it is an object of the present invention to provide a device of unitary construction to be carried in a magnetic leech device whereby, by operation of the device, the firing circuit of the magnetic leech device is armed at a predetermined depth by a hydrostatic pressure responsive switch, the leech device is automatically detached from the hydrofoil from which it depends at the instant the leech clings to marine mine, and the magnetic leech device explosive charge is detonated at a predetermined time interval after the detachment thereof thereby allowing the hydrofoil and the towing vehicle to move a safe distance beyond the place where the magnetic leech device became detached prior to detonation of the explosive charge.

It is another object of the present invention to provide an improved control device for a magnetic leech device F" 3,1953%? Patented July 27, 1965 which is considerably miniaturized and simplified at no expense to reliability, manufacturing costs, and safety.

Various other objects and advantages will appear from the following description of one embodiment of the invention, and the most novel features thereof will be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawings:

FIG. 1 represents an isometric view of a magnetic leech device as suspended in an operative position from a hydrofoil;

FIGS. 2a and 2b represent a larger view of the squib actuated connector of the magnetic leech device;

FIG. 3 represents a cross sectional view of a hydrostatic switch and timer mechanism of the magnetic leech device, the section through the mechanism being taken substantially along its cylindrical axis;

FIG. 4 represents a cross sectional view taken on the line 4-4 of FIG. 3;

FIG. 5 is an end view of the hydrostatic switch and timer mechanism as viewed along the lines 55 of FIG. 4, the bottom plate being removed;

FIG. 6 represents a fragmentary cross sectional view of the hydrostatic switch and timer mechanism, the sectional view being taken along the line 6-6 of FIG. 5; and

FIG. 7 is a schematic line diagram of the electrical circuit interconnecting the electrical elements within the hydrostatic switch and timer mechanism and the squib actuated connector of the magnetic leech device of the present invention.

In the illustrated embodiment of the invention, the magnetic leech assembly 16 depends from a hydrofoil (not shown) having a streamer extending downwardly therefrom and terminating in a connector ring 11, as shown in FIG. 1. A bridle 12 which forms a single point of connection at the upper end thereof, supports an explosive charge and magnet at convenient points on the housing 13 thereof. A squib actuated release clip 14 interconnects the ring 11 and the bridle 12. The three flexible suspending members of the bridle are so disposed and of such length as to maintain the longitudinal axes of the charge and magnet housing 13 parallel to the flow stream and directed thereinto. A pair of guide vanes 16 stabilize the housing laterally. The rear end of the charge and magnet housing 13 includes a receptacle 17 for receiving the hydrostatic switch and timer mechanism, shown generally by the numeral 13. A shielded cable 19 connects the mechanism 18 to the release clip 14. The general construction of the charge and magnet housing is disclosed in the above-mentioned application Serial No. 793,939.

Release clip 14 is illustrated in the closed and opened positions, respectively, in FIGS. 2a and 2b, and comprises flat strip of steel or other spring material bent into a clip or bifurcated spring 21 with suitable jaws 22 formed at the open end thereof. In the normal position, jaws 22 stand open and the spring must be urged to the closed position. Dowel couplings 23, 24 are offset on spring 21 so that they nest in the spring closed position. A dowel pin 26 inserted through an open-end dowel hole 27 in coupling 23 into a closed-end dowel hole 28 in coupling 24- secures the spring in the closed position. Pin 26 is hollow at the end thereof inserted into closed-end dowel hole 28 and includes an electrically energized explosive charge pocketed therein. Cable 19 functions to couple a low energy electrical pulse to charge 29 from hydrostatic switch and timer mechanism 18 to thereby detonate the charge causing pin 26 to be ejected from couplings 23, 24. Spring 21 then is biased to the open position, as shown in FIG. 2b, thereby disengaging jaws 22 from connector ring 11 releasing leech assembly 10 from the hydrofoil.

Now referring to FIGS. 3, 4, 5 and 6, hydrostatic switch and timer mechanism 18 is shown in the safe and unarmed condition. The main supporting member of the mechanism is a cylindrical housing having an upper portion 30 and a lower electrically insulative portion 31. A top plate 32 and a bottom plate 33 are fixed to the housin to support elements contained therein. A cylindrical hole 36 parallel to the cylindrical axis of the housing extends therethrough and slidably engages a piston 37. Piston 37 is connected at its upper end to a diaphragm 38 which is sealingly connected between the top of housing portion 30 and the top plate 32. A shaft 39 is fixed to the upper end of piston 37 and extends through an aperture in top plate 32. Holes 41 permit fluid pressure to act on the total area of piston 37 and diaphragm 38. Shaft 39 is maintained in the upward position by a ball detent 42 urged outwardly from shaft 39 against a stop by an arming safety pin 43. A second safety lock includes an arming wire 44 extending through shaft 39 and abutting top plate 32. Thus diaphragm 38 is restrained against moving the piston 37 and shaft 39 until the safety arming wire 44 and safety pin 43 are removed from shaft 39 to allow the ball detent 42 to retract and permit hydrostatic pressure to depress shaft 39 into the housing.

An electrically detonated explosive charge 46 is contained within a receptacle 47 in piston 37 which opens to cylinder wall 36. An aperture 48 in housing portion 31 communicates between cylinder 36 and an explosive charge of the leech which surrounds the housing. Aperture 48 is so oriented that when the hydrostatic pressure reaches a predetermined value piston 37 will have been depressed so that receptacle 47 aligns with aperture 43 and exposes charge 46 to the charge in the leech whereby when charge 46 is detonated the leech charge is ignited.

The detonator charge 46 is energized through a pair of wiper contacts 56 and 57 which extend outwardly through piston 37 to engage a wiper bar 58 which is grounded to the upper housing 30. Wiper bar 58 is formed so that wiper contact 56 becomes ungr-ounded when it moves out of contact with the wiper bar as piston 37 moves downward. Contact 57 and wiper bar '58 remain engaged throughout the movement of piston 37. A second wiper bar 59 confronts contact 56 and makes electrical contact therewith when receptacle 47 is aligned with aperture 48 thereby electrically arming detonator charge 46, as may be seen by reference to FIG. 7.

The grounded wiper bar 58 is further connected to the negative terminal of a battery 61 while Wiper bar 59 is extended laterally to engage one side of a water soluble wafer 62 (FIG. 7). The other side of wafe- 62 engages a loose spring 63 which is urged toward bar 59 but is maintained separated therefrom by the thickness of wafer 62. -As shown sch matically in FIG. 7, spring 63 is connected to the positive terminal of battery 61. Water 62 is contained in a chamber 64 which is sealed against communication with surrounding water except for an ejectable 66. Plug 66 abuts and seals an aperture in Wall 31 and at the same time abuts an electrically detonated timer squib 67 in the sealed position as may be seen by reference to FIG. 6. Squib 67, which is electrically connected by conductors 68 and 69 through spring 63 to a source of electrical energy, as shown schematically in FIG. 7, functions when energized to ej ct plug 66 from the aperture in wall 31.

Electrically detonated charge 29 of release clip 14- is connected in parallel to .the timer squib 67 through cable 19 by means of a plug in connector shown generally by reference numeral 71 in FIG. 3. Connector 71 includes a terminal 72 connected to the shield of cable 19, one of a pair of prongs 53 (FIGS.'4 and and to grounded wiper bar 58. The center wire of cable 19 connects through a spring loaded plunger 73 which in turn conmeets to the other prong '53 when the connector is full inserted.

all

The operation of the device should now be apparent. In the safety position, as illustrated, the contacts 56 and 57 of the detonator charge 46 are both shorted by the grounded Wiper bar 58 thereby preventing stray electrical energy from causing a premature explosion. The fuse becomes partly armed by manually withdrawing the safety pin 43, which unlocks the shaft 39, and by removing the safety pin 44, which allows the detent ball to move inwardly to allow the shaft 39 to move downwardly when any pressure is exerted thereon. Such a force may be hydrostatic head as caused when the device becomes submerged in water. The device finally becomes fully armed when a predetermined force, such as 20 feet of hydrostatic pressure, is exerted on the shaft 39, whereupon the detonator charge 46 is placed directly in line with the leech charge through the aperture 48 in housing portion 31. Simultaneously, contact 56 engages a second wiper bar 59 while wiper contact 57 remains connected to the ground wiper bar 58 whereby a secondary series electrical circuit including battery 61, charge 46, and wafer 62 is established.

It the device should return to the surface of the water before detonation, a pair of return springs 51 and 52 acting on extension arms 54 of piston 37 (FIG. 4) will raise the detonator charge to a safe position out of alignment with aperture 48. After the secondary circuit is established and the detonator charge 46 is in the ali ned and armed position with respect to aperture 43, which, as mentioned above, occurs when the device reaches a predetermined depth below the surface of the water, then electrical impulse generated by coils in the magnetic leech upon contact with a ferromagnetic object function to fire the release clip charge 29 and the timer squib 67 whereby the magnetic leech device is detached from the streamer rod ring 11 and plug 66 is ejected so that water can fill the timer chamber 64 and begin to dissolve the wafer 62. After a predetermined time interval necessary to completely dissolve the wafer 62, for instance ten minutes, spring 63 will compress against the second Wiper bar extension 59 to complete a circuit between the battery 61 and the detonator charge 46 thereby causing the detonator charge 46 to explode and detonate the leech charge, which in turn functions to destroy the object to which the magnetic leech initially clung.

The simplified manner in which the several component parts cooperate to perform the many functions required in use with antimine weapons inherently affords miniaturization of the control device so the overall size thereof is commensurate with the size limitations dictated by the magnetic leech device. By way of illustration, a control mechanism was built according to the invention having a housing with an outside diameter of approximately 1 /4 inches and an overall length exclusive of the connector 71 of about 1 inch, and a device of high precision accuracy and reliability was also attained. The release clip, also by its specific construction provides an almost instantaneous separation.

it will be understood, of course, that various changes in the details, materials, steps and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

What is claimed is:

1. In a release, arming and tiring control mechanism for an underwater explosive charge of the type depending from a hydrofoil and having a magnet and coil means adapted for attracting the charge to an underwater ferromagnetic object and for generating an electrical signal upon contact with the object, the combination comprising: a bifurcated spring member having opposed jaws formed on its open end to close about a connecting member fixed to the hydrofoil when said spring member is urged to the closed position, a first coupling fixed to the inner face of one leg of said spring member and having arearso a dowel hole extending therethrough, a second coupling fixed to the inner face of the other leg of said spring member and having a closed-end dowel hole extending thereinto, said couplings being offset relative to each other so that the dowel holes align to form a continuous closed end hole when said member is urged to the closed position, a dowel pin insertable in the continuous hole for maintaining said spring member in the closed position, an electrically detonated charge embedded in the insertion end of said dowel pin and exposed to the closed end of the continuous hole, a hydrostatic switch and timer housing externally formed to be inserted in the underwater explosive charge with a surface exposed to the surrounding fluid, a piston slidable in said housing movable by the fluid pressure, force means disposed between said housing and said piston opposing the fluid pressure and normally maintaining said piston at one end of its travel, a shaft fixed to said piston and axially extending therefrom through said exposed surface of said housing, a ball movable within a radial hole in said shaft, said shaft including an axial hole open at the exposed end thereof and communicating with said radial hole, a safety pin insertable the full length of the axial hole thereby urging said ball means to the outer end of the radial hole, said radial hole being of reduced size at its outer end whereby a portion of said ball protrudes to prevent movement of said piston when at said one end of travel, a first chamber in said piston having an opening at the side of said piston but sealed by the wall through which said piston slides, an opening in the wall positioned so as to provide communication between said first chamber and the underwater explosive charge when said piston is at the other end of its travel and said openings are aligned, an electricallydetonated charge contained in said first chamber, a second chamber in said housing communicating externally to the surrounding fluid by an ejectable plug, an electricallydetonated cartridge fixed between said housing and said plug for producing an ejection force, two movable electrical contacts resiliently connected to said piston and formed to engage the underwater explosive charge coil means when said piston is at said other end of its travel, first conductor means electrically connecting said dowel pin charge and said plug-ejecting cartridgein series whereby said dowel pin and said plug are simultaneously ejected when the magnet of said underwater explosive charge contacts a ferromagnetic object, a water-soluble element contained within said second chamber and disposed between two electrical contacts, at least one of said contacts having resilient means for biasing the contacts toward each other, an electrical supply contained within said housing, a slidable contact connected to said charge of said first chamber and a stationary contact fixed to said housing, said slidabie contact completing a circuit with said stationary contact when said piston is at said other end of its travel, and second conductor means electrically connecting said contacts of said element, said battery, and said charge in said first chamber in series whereby said charge in said first chamber is detonated when said element dissolves and said piston is at said other end of its travel.

2. in a control mechanism for an underwater exposive charge of the type depending from a hydrofoil and having a magnet and coil means adapted for attracting the charge to an underwater ferromagnetic object and for generating an electrical signal upon contact with the object, the combination comprising: a bifurcated spring member formed on its open end to close about a connecting member fixed to the hydrofoil when said spring member is urged to the closed position, a pair of couplings each fixed to the opposite inner faces of said spring member, one of said pair having a hole extending therethrough and the other of said pair having a closed-end hole extending thereinto, said couplings positioned relative to each other so that the holes align to form a continuous closed-end hole when said member is urged to the closed position, a pin insertable in the continuous hole for maintaining said spring member in the closed position, a first detonator in the insertion end of said pin and exposed to the closed end of the continuous hole, a housing externally formed to be inserted in the underwater explosive charge with a surface exposed to the surrounding fluid, a slidable piece in said housing movable by the fluid pressure, force 1 cans disposed between said housing and said piece opposing the fiuid pressure and normally maintaining said piece at one end of its travel, an extended portion of said piece axially extending therefrom through said surface having a radial hole communicating at a right angle with an axial hole therein, said holes being open at their noncommunicating outer ends, locking means movable within said radial hole, a safety pin insertable in the axial hole to the radial hole thereby urging said locking means to the outer end of the radial hole, the radial hole being of reduced size at its outer end whereby only a portion of said locking means protrudes to prevent movement of said piece when at said one end of travel, a first chamber in said piece having an opening sealed by the housing wall over which said piece slides, an opening in said housing positioned so as to provide communication between said first chamber and the underwater explosive charge when said piece is at the other end of its travel, a second detonator contained in said first chamber, a second chamber in said housing communicating externally by an ejectable plug, a third detonator fixed between said housing and said plug for producing an ejection force, movable electrical contacts connected to said piece and formed to engage the underwater explosive charge coil means when said piece is at the other end of its travel, first conductor means electrically connecting said first and third detonators, whereby said pin and said plug are simultaneously ejected when the magnet of said underwater explosive charge contact a ferromagnetic object, a water-soluble Wafer contained within said second chamber and disposed between two electrical contacts resiliently biased toward each other, an electrical supply contained within said housing, a slidahis contact connected to said second detonator and a stationary contact fixed to said housing, said lidable contact completing a circuit with said stationary contact when said piece is at said other end of its travel, and second conductor means electrically connecting said contacts of said element, said battery, and said second detonator, in series whereby said second detonator is fired when said element dissolves and said piece is at said other end of its travel.

3. In a control mechanism for an underwater explosive charge of the type depending from a hydrofoil and having a magnet and coil means adapted for attracting the charge to an underwater ferromagnetic object and for generating an electrical signal upon contact with the object, the combination comprising: a bifurcated spring member formed at its open end to close about a connecting element fixed to the hydrofoil when it is urged to the closed position, a first receptacle fixed to the inner face of one leg of said member, a second receptacle fixed to the inner face of the other leg of said member, said receptacles being positioned relative to each other so that they align to form a continuos hole when said member is urged to the closed position, pin means insertable in said continuous hole for maintaining said spring member in the closed position, electrically activated mean for ejecting said pin means from the continuous hole, a housing insertable in the underwater explosive charge having one side exposed to the surrounding fluid, a fluid-pressure responsive piston means slidable in said housing and normally maintained at one end of its travel, said piston means axially extending through said exposed side of said housing, an electrically activated detonator means contained in said piston means and adjacent to the housing wall over which said piston means slides, an opening in said housing wall positioned so as to provide communication between said detonator means and the underwater explosive charge, a

timer in said housing of the type electrically initiated, electrical contact means operatively connected to said piston and formed to engage the underwater explosive charge coil means when said piston means i at its other end of travel, first conductor means electrically connecting said ejecting means and said timer in series whereby said pin means is ejected and said timer initiated when the magnet of said underwater explosive charge contacts a ferromagnetic object, said timer having contacts which close after a prescribed time interval, an electrical supply contained within said housing, contact means actuated by said piston means for completing a circuit when said piston means is at said other end of its travel, and second conductor means electrically connecting said timer contacts with said battery, and said detonator whereby said detonator is fired when said timer contacts close and said piston means is at said other end of its travel.

4. In a control mechanism for an underwater explosive charge of the type depending from a hydrofoil and having a magnet and coil means adapted for attracting the charge to an underwater ferromagnetic object and for generating an electrical signal upon contact with the object, the combination comprising: a bifurcated resilient member formed on its open end to close about a connecting member fixed to the hydrofoil when said member is urged to closed position, pin means insertable in said member for maintaining said member in the closed position, an electrical means for ejecting said pin means, a housing insertable in the underwater explosive charge with a portion exposed to the surrounding fluid, a pressureresponsive slidable means in said housing normally maintained at one end of its travel, said slidable means axially extending through said exposed portion, electrical detonator means in said slidable means, an opening in said housing positioned so as to expose said detonator means to the underwater explosive charge when said slidable means is at the other end of its travel, electrical timer means in said housing having contacts which close after a time interval, electrical contacts operatively connected to said slidable means engaging the underwater explosive charge coil means when said slidable means is at the other end of its travel, first conductor means electrically connecting said ejecting means and said timer whereby said pin means is ejected and said timer initiated when the magnet of said underwater explosive charge contacts a ferromagnetic objects, an electrical supply contained within said housing, contact means operative when said slidable means is at said other end of its travel, and second conductor means electrically connecting said timer contacts in series with said battery and said detonator means whereby said detonator means is fired when said timer contacts close and said slidable means is at said other end of its travel.

5. An arming and firing control mechanism for an underwater explosive charge having a magnet and coil means adapted for attracting the charge to an underwater ferromagnetic object and for generating an electrical signal upon contact with the object, the combination comprising: a housing externally formed to be inserted in the underwater explosive charge with one end exposed to the surrounding fluid, a piston slid-able in said housing movable by the fluid pressure, force means disposed between said housing and said piston opposing the fluid pressure and normally maintaining said piston at one end of its travel, a shaft fixed to said piston and axially extending therefrom through said exposed end of said housing, a ball movable within a radial hole in said shaft, said shaft including an axial hole open at the exposed end thereof and communicating with said radial hole, a safety pin insertable the full length of the axial hole whereby urging said ball means to the outer end of the radial hole, said radial hole being of reduced size at its outer end whereby a portion of said ball protrudes to prevent movement of said piston when at said one end of travel, a first chamber in said piston and sealed at one end by the housing surface over which said one end of said chamber slides, a hole in said housing positioned so as to provide communication between said first chamber and the underwater explosive charge, an electrically-detonated charge contained in said first chamber when said piston is at the other end of its travel, a second chamber in said housing communicating externally to the surrounding fluid by an ejectable plug, an electrically-detonated cartridge fixed between said housing and said plug for producing an ejection force, two movable electrical contacts resiliently connected to said piston and formed to engage the underwater explosive charge coil means when said piston is at the other end of its travel, first conductor means electrically connecting said plug-ejecting cartridge in series with said two contacts, whereby said plug is ejected when the magnet of said underwater explosive charge contacts a ferromagnctic object, a water-soluble element contained within said second chamber and disposed between two electrical contacts, at least one of said contacts having resilient means for biasing the contacts toward each other, an electrical supply contained within said housing, a slidable contact connected to said charge of said first chamber and a stationary contact fixed to said housing, said slidable contact completing a circuit with said stationary contact when said piston is at said other end of said piston travel, and second conductor means electrically connecting said contacts of said element, said battery, said charge in said piston, and said movable and stationary contacts in series, whereby said charge in said piston is detonated when said element dissolves and said piston is at said other end of its travel.

6. A control mechanism for an underwater explosive charge having a magnet and coil means adapted for attracting the charge to an underwater ferromagnetic object and for generating an electrical signal upon contact with the object, the combination comprising: a housing externally formed to be inserted in the underwater explosive charge with a surface exposed to the surrounding fluid, a slidable piece in said housing movable by the fluid pressure, force means disposed between said housing and said piece opposing the fluid pressure and normally maintaining said piece at one end of its travel, an extended portion of said piece axially extending therefrom through said surface having a radial hole communicating at a right angle with an axial hole therein, said holes being open at their noncommunicating outer ends, locking means movable within said radial hole, a safety pin insertable in the axial hole to the radial hole thereby urging said locking means to the outer end of the radial hole, the radial hole being of reduced size at its outer end whereby only a portion of said locking means protrudes to prevent movement of said piece when at said one end of travel, a first chamher in said piece having an opening sealed by the housing wall over which said piece slides, an opening in said hous ing positioned so as to provide communication between said first chamber and the underwater explosive charge when said piece is at the other end of its travel, a first detonator contained in said first chamber when said piece is at the other end of itstravel, a second chamber in said housing communicating externally to the surrounding fluid by an ejec-table plug, a second detonator fixed between Said housing and said plug for producing an ejection force, movable electrical contacts connected to said piece and formed to engage the underwater explosive charge coil means when said piece is at the other end of its travel, first conductor means electrically connecting said second detonator with said contacts whereby said plug is ejected when the magnet of said underwater explosive charge contacts a ferromagnetic object, a water-soluble water contained within said second chamber and disposed between two electrical contacts resiliently biased toward each other, an electrical supply contained within said housing, a slidable contact connected to said first detonator and a stationary contact fixed to said housing, said slidable contact completing a circuit with said stationary contact when said piece at said other end of its travel, and second conductor means electrically connecting said contacts of said element, first deton-ator, and said battery in series whereby said first detonator is fired when said element dissolves and said piece is at said other end of its travel;

7. An arming and firing control mechanism for an underwater explosive charge having a magnet and coil means adapted for attracting the charge to an underwater ferromagnetic object and for generating an electrical signal upon contact with the object, the combination comprising: a housing insertable in the underwater explosive charge having one side exposed to the surrounding fluid, a fluid-pressure responsive piston means slidable in said housing and normally maintained at one end of its travel, said piston means axially extending through said exposed side of said housing, an electrically activated detonator means contained in said piston means and adjacent to the housing wall over which said piston means slides, an opening in said housing wall positioned so as to provide communication between said detonator means and the underwater explosive charge, a timer in said housing of the type electrically initiated, electrical contact means resiliently connected to said piston and formed to engage the underwater explosive charge coil means when said piston means is at its other end of travel, first conductor means electrically connecting said timer with said contact means whereby said timer is initiated when the magnet of said underwater explosive charge contacts a ferromagnetic object, said timer having contacts which close after a prescribed time interval, an electrical supply contained within said housing, contact means actuated by said piston means for completing a circuit when said piston means is at said other end of its travel, and second conductor means electrically connecting said timer contacts with said battery and said detonator whereby said detonator is fired When said timer contacts close and said piston means is at said other end of its travel.

References Cited by the Examiner UNITED STATES PATENTS 2,436,394 2/48 Maltby et al. 102-l8 2,703,052 3/55 Glennon et 'al 102-18 2,926,565 3/60 Thorness 891 2,938,429 5/60 Jaglowski et al. 891

BENJAMIN A. BORCHELT, Primary Examiner.

ARTHUR M. HORTON, SAMUEL FEINBERG, SAM- UEL BOYD, Examiners. 

1. IN A RELEASE, ARMING AND FIRING CONTROL MECHANISM FOR AND UNDERWATER EXPLOSIVE CHARGE OF THE TYPE DEPENDING FROM A HYDROFOIL AND HAVING A NAGNET AND COIL MEANS ADAPTED FOR ATTRACTING THE CHARGE TO AN UNDERWATER FERROMAGNETIC OBJECT AND FOR GENERATING AN ELECTRICAL SIGNAL UPON CONTACT WITH THE OBJECT, THE COMBINATION COMPRISING: A BIFURCATED SPRING MEMBER HAVING OPPOSED JAWS FORMED ON ITS OPEN END TO CLOSE ABOUT A CONNECTING MEMBER FIXED TO THE HYDROFOIL WHEN SAID SPRING MEMBER IS URGED TO THE CLOSED POSITION, A FIRST COUPLING FIXED TO THE INNER FACE OF ONE LEG OF SAID SPRING MEMBER AND HAVING A DOWEL HOLE EXTENDING THERETHROUGH, A SECOND COUPLING FIXED TO THE INNER FACE OF THE OTHER LEG OF SAID SPRING MEMBER AND HAVING A CLOSED-END DOWEL HOLE EXTENDING THEREINTO, SAID COUPLINGS BEING OFFSET RELATIVE TO EACH OTHER SO THAT THE DOWEL HOLES ALIGN TO FORM A CONTINUOUS CLOSED-END HOLE WHEN SAID MEMBER IS URGED TO THE CLOSED POSITION, A DOWEL IN THE CONTINUOUS HOLE FOR MAINTAINING SAID SPRING MEMBER IN THE CLOSED POSITION, AN ELECTRICALLY DETONATED CHARGE EMBEDDED IN THE INSERTION END OF SAID DOWEL PIN AND EXPOSED TO THE CLOSED END OF THE CONTINUOUS HOLE, A HYDROSTATIC SWITCH AND TIMER HOUSING EXTERNALLY FORMED TO BE INSERTED IN THE UNDERWATER EXPLOSIVE CHARGE WITH A SURFACE EXPOSED TO THE SURROUNDING FLUID, A PISTON SLIDABLE IN SAID HOUSING MOVABLE BY THE FLUID PRESSURE, FORCE MEANS DISPOSED BETWEEN SAID HOUSING AND SAID PISTON OPPOSING THE FLUID PRESSURE AND NORMALLY MAINTAINING SAID PISTON AT ONE END OF ITS TRAVEL, A SHAFT FIXED TO SAID PISTON AND AXIALLY EXTENDING THEREFROM THROUGH SAID EXPOSED SURFACE OF SAID HOUSING, A BALL MOVABLE WITHIN A RADIAL HOLE IN SHAFT, SAID SHAFT INCLUDING AN AXIAL HOLE OPEN AT THE EXPOSED END THEREOF AND COMMUNICATING WITH SAID RADIAL HOLE, A SAFETY PIN INSERTABLE THE FULL LENGTH OF THE AXIAL HOLE THEREBY URGING SAID BALL MEANS TO THE OUTHER END OF THE RADIAL HOLE, SAID RADIAL HOLE BEING OF REDUCED SIZE AT ITS OUTER END WHEREBY A PORTION OF SAID BALL PROTRUDES TO PREVENT MOVEMENT OF SAID PISTON WHEN AT SAID ONE END OF TRAVEL, A FIRST CHAMBER IN SAID PISTON HAVING AN OPENING AT THE SIDE OF SAID PISTON BUT SEALED BY THE WALL THROUGH WHICH SAID PISTON SLIDES, AN OPENING IN THE WALL POSITIONED SO AS TO PROVIDE COM- 